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Re: Best practice for overridden initializers in subclasses
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Re: Best practice for overridden initializers in subclasses


  • Subject: Re: Best practice for overridden initializers in subclasses
  • From: Andy Lee <email@hidden>
  • Date: Tue, 25 Mar 2008 19:26:52 -0400

A similar question was asked recently. To paraphrase (and slightly correct) my reply:

I do essentially this:

- (id)init
{
   NSLog(@"%@ -- '%@' is not the designated initializer",
         [self class],
         NSStringFromSelector(_cmd));
   [self release];
   return nil;
}

You can imagine wrapping the three statements in a macro, and/or throwing an exception or putting in a breakpoint.

Since there's no way to enforce designated initializers at compile time, and there may be no way for you to recover gracefully at runtime, the best you can do is catch the error wherever possible during development and testing.

--Andy


On Mar 25, 2008, at 6:01 PM, Andy Klepack wrote:

I have a subclass of NSObject that provides its own designated initializer that allows client code to configure an instance with initial values. Instances of the class itself are immutable. At the same time, instances where no initial values are supplied do not make conceptual sense.

I'm wondering how to deal with overriding the 'init' method of NSObject. There's really no sensible default values that I could have init pass along to my designated initializer. It doesn't make sense for clients to call 'init' and I'm debating whether to return nil, throw some sort of exception, make the instance 'dead' and essentially do nothing, or to do something else..

Anyone have a recommendation for the best practice in this case?
-Andy

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